Drop hammer impact tensile test device and method for prestressed steel strand

Abstract

The invention discloses a drop hammer impact tensile test device and method for a prestressed steel strand, and relates to the field of drop hammer impact test devices.The drop hammer impact tensile test device comprises a connecting steel frame connected to a reaction frame cross beam and a drop hammer suspended below the connecting steel frame through an unhooking device, a through hole is formed in the center of the drop hammer, and the steel strand penetrates through the drop hammer through the through hole; the upper anchoring end of the steel strand is fixed to the connecting steel frame, and an anchoring end bearing disc is installed at the lower anchoring end of the steel strand. In the first state, the drop hammer is kept static through the unhooking device, and in the second state, the drop hammer is released from the unhooking device, freely falls along the steel strand and impacts the anchoring end bearing disc. According to the device, the drop hammer is matched with the steel strand, so that the falling path of the drop hammer coincides with the steel strand, the friction resistance borne by the drop hammer during falling is reduced, and the accuracy, efficiency and safety of the prestressed steel strand drop hammer impact tensile test can be improved by adopting the device and the method.

Description

Technical Field

[0001] The invention relates to the field of drop-hammer impact testing devices, and in particular to a drop-hammer impact tensile testing device and method for prestressed steel strands. Background Art

[0002] The drop weight impact tensile test is a test method for evaluating the performance and durability of materials under impact loads. Its basic principle is to use the kinetic energy generated by the drop weight to impact load the steel strand body and record the force and deformation of the falling body during the impact. The test system mainly consists of two parts: the mechanical structure part and the data monitoring part. The mechanical structure part uses a clamp to hang one end of the test cable body on the portal steel frame, and the other anchor end hangs freely. Then the drop weight is lifted to the specified height and released through the unhooking device. After free fall, the drop weight hits the load-bearing plate at the anchor end of the steel strand to achieve the purpose of impact tensile cable body. After the drop weight falls, the data monitoring part starts to work, collects the data signal of the drop weight through the acceleration sensor, and records and analyzes the data through the data analysis instrument. Through the joint work of the above parts, the test system can complete the whole process of impact collision and data collection.

[0003] In the prior art drop weight tester, a guide rod is usually used to restrain the drop weight to prevent it from deflecting and rolling when falling. However, in the drop weight tester with this structure, there is friction resistance between the drop weight and the guide rod, which makes it difficult and complicated to start the drop weight unhooking, and the resistance cannot be accurately measured, resulting in inaccurate data of the drop weight impact test. In addition, as the number of tests increases, the guide rod will wear out quickly, resulting in a reduction in the life of the tester. Summary of the invention

[0004] The object of the present invention is to provide a drop-hammer impact tensile test device and method for prestressed steel strands, so as to solve the above-mentioned technical problems existing in the prior art.

[0005] To achieve the above-mentioned objectives, on the one hand, the present invention provides a drop-hammer impact tensile testing device for prestressed steel strands, comprising a connecting steel frame connected to a reaction frame crossbeam, and a drop hammer suspended below the connecting steel frame through a decoupling device, wherein a through hole is provided at the center of the drop hammer, and the steel strand passes through the drop hammer from the through hole, the upper anchor end of the steel strand is fixed to the connecting steel frame, and an anchor end bearing plate is installed on the lower anchor end; in a first state, the drop hammer is kept stationary by the decoupling device, and in a second state, the drop hammer is released from the decoupling device, freely falls along the steel strand, and impacts the anchor end bearing plate.

[0006] According to the drop-hammer impact tensile testing device for prestressed steel strands of the present invention, the connecting steel frame includes a first steel plate, a second steel plate, a third steel plate and a fourth steel plate spaced from bottom to top, the first steel plate, the second steel plate, the third steel plate and the fourth steel plate are horizontally fixed on four screw rods by locking nuts, the third steel plate and the fourth steel plate are respectively pressed against the bottom and top surfaces of the reaction frame crossbeam, the upper anchor end of the steel strand is connected to the center of the second steel plate, the decoupling device is connected to the first steel plate, and a U-shaped notch is opened in the center of the first steel plate to accommodate the steel strand passing through.

[0007] According to the drop-hammer impact tensile testing device for prestressed steel strands of the present invention, two decoupling devices are provided, and the two decoupling devices are symmetrically arranged on both sides of the U-shaped notch.

[0008] According to the drop-hammer impact tensile testing device for prestressed steel strands of the present invention, the decoupling device comprises a device body, a decoupling mechanism movable in the device body, and a passive hanger clamped in the decoupling mechanism, the drop-hammer is fixedly connected to the bottom of the passive hanger by connecting a steel wire rope; the inner cavity of the device body has a reduced diameter section near the top, the reduced diameter section comprises two reduced diameter inclined surfaces facing each other; the decoupling mechanism comprises a central block sliding in the inner cavity of the device body, movable blocks are symmetrically hinged on both sides of the central block, a spring is connected between the two movable blocks, in an initial state, the spring pulls the bottom ends of the two movable blocks together to clamp the passive hanger between the two movable blocks, an unlocking steel wire rope is connected above the central block, the unlocking steel wire rope is pulled, the two movable blocks ascend to the reduced diameter section, the reduced diameter inclined surfaces guide the top ends of the two movable blocks together to make the bottom ends of the two movable blocks move away from each other, and the passive hanger is disengaged from between the two movable blocks.

[0009] According to the drop-hammer impact tensile testing device for prestressed steel strands of the present invention, a plug-in is supported above the second steel plate, a weight groove is opened on one side of the plug-in and radially penetrates to the center thereof, the central inner diameter of the weight groove is smaller than the outer diameter of the anchor end of the steel strand, and a reserved hole is opened in the center of the second steel plate to pass through the top and bottom, and the upper anchor end of the steel strand is supported above the plug-in through the reserved hole.

[0010] According to the drop-hammer impact tensile testing device for prestressed steel strands of the present invention, a positioning pin is protruded from the bottom of the plug-in, and a positioning groove cooperating with the positioning pin is formed on the second steel plate.

[0011] The drop-hammer impact tensile testing device for prestressed steel strands according to the present invention further comprises a gravity accelerometer mounted on the drop-hammer.

[0012] According to the drop weight impact tensile testing device for prestressed steel strands of the present invention, the third steel plate and the fourth steel plate are cross-shaped plates.

[0013] According to the drop-hammer impact tensile testing device for prestressed steel strands of the present invention, the anchor end load-bearing plate comprises two semicircular load-bearing plates which wrap the steel strands in the middle from both sides of the steel strands, the two semicircular load-bearing plates are connected by bolts and supported on the lower anchor end of the steel strands.

[0014] According to the drop-hammer impact tensile testing device for prestressed steel strands of the present invention, guide members are detachably mounted at both ends of the through hole, a guide hole is opened in the center of the guide member, and the steel strand passes through the guide member and the drop-hammer from the guide hole.

[0015] According to the drop-hammer impact tensile testing device for prestressed steel strands of the present invention, the drop hammer comprises a plurality of hammer bodies, the plurality of hammer bodies are connected in sequence in a vertical direction, and the through holes of the hammer bodies are interconnected, and the weight of the drop hammer can be adjusted by increasing or decreasing the number of the hammer bodies.

[0016] On the other hand, the present invention provides a drop weight impact tensile test method, testing the drop weight impact tensile test device for prestressed steel strands of the present invention, comprising the following steps:

[0017] S1. Assemble and connect the steel frame;

[0018] S2, installing the assembled connecting steel frame onto the reaction frame crossbeam;

[0019] S3, laying buffer sand on the ground below the connecting steel frame;

[0020] S4. Pass the upper anchorage end of the steel strand through the drop weight and fix it on the connecting steel frame;

[0021] S5. Send the drop weight to the preset height through the lifting device and fix it to the unhooking device by connecting the wire rope. After the drop weight is stable, release the lifting device to complete the preparation work before the test;

[0022] S6. Turn on the test instrument, release the unhooking device, release the drop hammer, complete a test and record the test data;

[0023] S7, repeat steps S4-S6 to complete 3-5 groups of experiments;

[0024] S8. After the test is completed, dismantle the test device.

[0025] Compared with the prior art, the present invention at least discloses the following beneficial effects:

[0026] The device of the present invention cooperates the drop hammer with the steel strand so that the falling path of the drop hammer coincides with the steel strand, thereby reducing the friction resistance encountered by the drop hammer. The device and method of the present invention can improve the accuracy, efficiency and safety of the drop hammer impact tensile test of the prestressed steel strand. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 It is a front view of the test device of the present invention;

[0029] Figure 2 It is a right side view of the test device of the present invention;

[0030] Figure 3 is an axonometric diagram of the test device of the present invention;

[0031] Figure 4 It is a schematic diagram of the connection between the anchor end bearing plate and the lower anchor end in the test device of the present invention;

[0032] Figure 5 It is a schematic diagram of the structure of the plug-in in the test device of the present invention;

[0033] Figure 6 A schematic diagram of a structure of a connecting steel frame in the test device of the present invention;

[0034] Figure 7 It is another structural schematic diagram of connecting steel frames in the test device of the present invention;

[0035] Figure 8 A diagram showing the connection relationship between the steel strand and other components in the test device of the present invention;

[0036] Fig. 9 A cross-sectional view of the decoupling device in the test device of the present invention Figure 1 ;

[0037] Fig.10 A cross-sectional view of the decoupling device in the test device of the present invention Figure 2 ;

[0038] Fig.11 It is a structural schematic diagram of the guide member A in the test device of the present invention;

[0039] Fig.12 It is a schematic diagram of the structure of the guide member B in the test device of the present invention.

[0040] In the figure: 1, first steel plate; 100, U-shaped notch; 2, second steel plate; 21, reserved hole; 22, positioning groove; 3, third steel plate; 4, fourth steel plate; 5, reaction frame beam; 6, locking nut; 7, screw; 8, upper anchor end; 9, plug-in; 91, positioning pin; 92, weight slot; 10, unhooking device; 101, device body; 102, reducing inclined surface; 103, center block; 104, movable block; 105, spring; 106, rotating shaft ; 107. Unlocking wire rope; 108. Passive hanger; 109. Connecting wire rope; 11. Drop weight; 12. Steel strand; 13. Anchor end load plate; 14. Lower anchor end; 15. Guide; 15a. A guide; 15a-1; A guide one; 15a-2. A guide two; 15b. B guide; 15b-1. B guide one; 15b-2. B guide two; 151. Guide hole; 152. Threaded hole; 16. Bolt. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Reference Figures 1 to 12 As shown, the present invention provides a drop-hammer impact tensile test device for prestressed steel strands, including a connecting steel frame, which is composed of four steel plates and screws 7 assembled by locking nuts 6. The whole is divided into four layers and three parts. The main function is to connect the steel strands 12 and the unhooking device 10 with the portal steel frame. The portal steel frame includes a reaction frame beam 5 supported between two vertical frames, and the connecting steel frame is installed on the reaction frame beam 5. A decoupling device 10 is provided on the connecting steel frame, and the decoupling device 10 is fixed on one of the steel plates, which can be the lowest steel plate. The decoupling device 10 is used to suspend a drop hammer 11. In the present embodiment, a drop hammer 11 is suspended below the decoupling device 10, and the drop hammer 11 is a through-hole hammer, that is, a through hole is opened in the center of the drop hammer 11, and a steel strand 12 passes through the through hole. The upper anchoring end 8 of the steel strand 12 is fixed on the connecting steel frame, and an anchoring end bearing plate 13 is installed on the lower anchoring end 14; in the first state, the drop hammer 11 is kept stationary by the decoupling device 10, and in the second state, the drop hammer 11 is released from the decoupling device 10, freely falls along the steel strand 12, and impacts the anchoring end bearing plate 13.

[0044] In this embodiment, if Figure 6 As shown, the connecting steel frame includes a first steel plate 1, a second steel plate 2, a third steel plate 3 and a fourth steel plate 4 which are spaced apart from bottom to top, and the first steel plate 1, the second steel plate 2, the third steel plate 3 and the fourth steel plate 4 are horizontally fixed on four screw rods 7 by locking nuts 6, and the third steel plate 3 and the fourth steel plate 4 are respectively pressed against the bottom and top surfaces of the reaction frame cross beam 5, and the upper anchoring end 8 of the steel strand 12 is connected to the center of the second steel plate 2, and the decoupling device 10 is connected to the first steel plate 1, and a U-shaped notch 100 is opened in the center of the first steel plate 1 to accommodate the steel strand 12 passing through.

[0045] In some embodiments, Figure 7 As shown, the third steel plate 3 and the fourth steel plate 4 are cross-shaped plates with added flanges, and the entire steel plate is formed in one piece. The steel plate with this structure can enhance the lateral stability of the entire connecting steel frame, so that the connecting steel frame can better cooperate with the reaction frame crossbeam 5; at the same time, the cross shape can reduce the dead weight of the steel plate compared to the traditional rectangle, and is convenient for disassembly and installation.

[0046] In this embodiment, the second steel plate 2 in the middle layer is a perforated steel plate with a reserved hole 21 and a positioning groove 22 in the center of the top surface. The second steel plate 2 is used for connecting the steel strand 12. The reserved hole 21 in the middle facilitates the upper anchoring end 8 of the steel strand 12 to penetrate from the bottom so as to be fixed on the second steel plate 2. The second steel plate 2 supports an insert 9 for fixing the steel strand 12 above. The insert 9 is in the shape of a weight, and a weight groove 92 is opened on one side thereof, which penetrates radially to the center thereof. Figure 5 The central inner diameter of the weight groove 92 is smaller than the outer diameter of the anchor end 8 on the steel strand 12, and a positioning pin 91 is protruded from the bottom of the plug-in 9, and the positioning pin 91 cooperates with the positioning groove 22 on the second steel plate 2 to form a positioning, and the upper anchor end 8 of the steel strand 12 passes through the reserved hole 21 and is supported above the plug-in 9.

[0047] In this embodiment, the bottom layer of the first steel plate 1 is a fixing layer for the drop hammer 11, and a U-shaped notch 100 is opened on the side of the first steel plate 1 to facilitate the passage of the steel strand 12. A decoupling device 10 is fixedly connected to the upper surface or the lower surface of the first steel plate 1. Preferably, two decoupling devices 10 are provided, and the two decoupling devices 10 are symmetrically arranged on both sides of the U-shaped notch 100. The two decoupling devices 10 operate synchronously and can be controlled by an unlocking wire rope 107.

[0048] In this embodiment, the drop hammer 11 is the core of the entire mechanical structure, and its external shape is a cylinder. A through hole is left at the center of the hammer surface, and the reserved hole 21 allows a single bundle of steel strands 12 to squeeze the anchor head through, so as to ensure the free shuttle of the steel strand 12 cable body. Compared with the traditional drop hammer test machine, the drop hammer 11 is controlled by a guide rail and vertically drops from the center position to impact the test piece. In the embodiment of the present invention, the steel strand 12 is suspended and placed at the center position of the drop hammer 11, coinciding with the falling trajectory of the drop hammer 11, and it is not appropriate to guide the drop hammer 11 by means of a guide rail. In this embodiment, the design without a slide rail not only reduces the impact of friction on the experiment, but also makes the drop distance of the drop hammer 11 no longer constrained by the slide rail, and the adjustment is more convenient. Each independent drop hammer 11 weighs 0.1 tons, and the weight of the hammer can be adjusted by increasing or decreasing the number of hammer bodies assembled. In addition, a screw 7 hole is reserved at the outer diameter of each hammer body for easy disassembly and assembly.

[0049] Further optimized solution, guide members 15 can be detachably installed at both ends of the through hole of the drop weight 11, a guide hole 151 is opened in the center of the guide member 15, and multiple (the number can be increased or decreased as needed) threaded holes 152 are opened around the guide hole 151 to achieve connection with the drop weight 11, and the steel strand 12 passes through the guide member 15 and the drop weight 11 from the through hole. The guide member 15 mainly plays the role of limiting and guiding, replacing the slide rail device of the traditional experimental system.

[0050] In order to make the hammer body fall along the predetermined track, two types of guide members 15 are designed in the embodiment of the present invention: a semi-cylindrical type and a semi-convex type, respectively. Fig.11 and Fig.12 shown.

[0051] Fig.11 A semi-cylindrical guide 15a is shown. Fig.11 (a) is the main view, (b) is the top view, and (c) is the isometric view. The A guide 15a is composed of two semicircular A guides 1 15a-1 and A guides 2 15a-2. The two semicircular blocks have semicircular grooves on the vertical surface. The combination of the two forms a guide hole 151 that allows the steel strand 12 to pass through.

[0052] Fig.12 A semi-convex B guide 15b is shown. Fig.12 (a) is the main view, (b) is the top view, and (c) is the isometric view. The B guide 15b is composed of two stepped semi-cylinders, namely, the B guide 1 15b-1 and the B guide 2 15b-2. The two stepped semi-cylinders have semi-circular grooves on the vertical surface. The two are combined to form a guide hole 151 that allows the steel strand 12 to pass through. The small end of the stepped semi-cylinder can be embedded in the circular concave grooves at both ends of the hammer body to achieve the combination with the hammer body.

[0053] According to a further optimization scheme, the drop-hammer impact tensile testing device for prestressed steel strands further comprises a gravity accelerometer mounted on the drop-hammer 11 .

[0054] A further optimized solution is that the drop hammer 11 includes a plurality of hammer bodies, each of which is connected in sequence in the vertical direction, for example, by a screw, a through hole is opened in the center of each hammer body, and the through holes of each hammer body are interconnected, and the weight of the drop hammer can be adjusted by increasing or decreasing the number of hammer bodies assembled.

[0055] In some embodiments, Fig. 9 and Fig.10 As shown, the unhooking device 10 includes a device body 101, an unhooking mechanism movable in the device body 101, and a passive hanger 108 clamped in the unhooking mechanism. The drop hammer 11 is fixedly connected to the bottom of the passive hanger 108 by connecting a steel wire rope 109; the inner cavity of the device body 101 has a reduced diameter section near the top, and the reduced diameter section includes two opposite reduced diameter inclined surfaces 102; the unhooking mechanism includes a central block 103 sliding in the inner cavity of the device body 101, and movable blocks 104 are symmetrically hinged on both sides of the central block 103. The two movable blocks 104 both include a hook end, an arc end and an intermediate hinged end located between the hook end and the arc end, and the intermediate hinged end is rotatably connected to both sides of the bottom of the central block 103 through a rotating shaft 106. A spring 105 is connected between the two movable blocks 104. In the initial state, the spring 105 pulls the bottom ends of the two movable blocks 104 together, clamping the passive hanger 108 between the two movable blocks 104. An unlocking wire rope 107 is connected above the center block 103. When the unlocking wire rope 107 is pulled, the two movable blocks 104 move upward to the reduced diameter section, and the reduced diameter slope 102 guides the top ends of the two movable blocks 104 to move closer together, so that the bottom ends of the two movable blocks 104 move away from each other, and the passive hanger 108 falls out from between the two movable blocks 104.

[0056] In this embodiment, the anchorage end weighing plate is located at the anchorage end where the steel strand 12 is freely hanging. After the hammer body falls freely, it collides with the anchorage end bearing plate 13 of the steel strand 12, thereby achieving the purpose of impacting and stretching the cable body. Figure 4 As shown, the anchor end load-bearing plate 13 includes two semicircular load-bearing plates with the steel strand 12 sleeved in the middle from both sides of the steel strand 12 . The two semicircular load-bearing plates are connected by bolts 16 and supported on the lower anchor end 14 of the steel strand 12 .

[0057] It should be understood that in practical applications, the decoupling device 10 may have a variety of structures, and may adopt the structure in this embodiment or may select other decoupling structures disclosed in the prior art.

[0058] The embodiment of the present invention further provides a drop weight impact tensile test method, using the drop weight impact tensile test device for prestressed steel strands, the test method comprises the following steps:

[0059] S1. Assemble and connect the steel frame; first assemble the first steel plate 1, the second steel plate 2, and the third steel plate 3 on the ground, wherein the spacing between the second steel plate 2 and the third steel plate 3 is 200 mm. The spacing between the second steel plate 2 and the first steel plate 1 is 100 mm, and each steel plate is fixed up and down by a M30 locking nut 6;

[0060] S2, installing the assembled connecting steel frame on the reaction frame cross beam 5; using the crane beam to lift the installed first steel plate 1, the second steel plate 2, and the third steel plate 3 to the reaction frame cross beam 5, and then docking and installing them with the fourth steel plate 4, so that the installation steel frame is fixed on the reaction frame cross beam 5;

[0061] S3, laying buffer sand on the ground below the connecting steel frame; laying buffer sand under the installation steel frame, and ensuring that the sand thickness is more than 30 cm at the thinnest point and more than 50 cm at the hammer landing point;

[0062] S4, passing the upper anchor end 8 of the steel strand 12 through the drop hammer 11 and fixing it on the connecting steel frame; passing the steel strand 12 through the drop hammer 11 on the ground, assembling the drop hammer 11, and installing a gravity accelerometer on the drop hammer 11; passing the upper anchor end 8 of the steel strand 12 through the second steel plate 2 of the mounting steel frame and fixing it on the second steel plate 2;

[0063] S5, send the drop hammer 11 to a preset height position through a lifting device, and fix it to the unhooking device 10 by connecting the steel wire rope 109, and release the lifting device after the drop hammer 11 is stable, completing the preparation work before the test; the drop hammer 11 is supported by a forklift, and after the steel strand 12 is fixed, the drop hammer 11 on the forklift is lifted to the bottom of the first steel plate 1 through the lifting device, and is suspended and fixed by the connecting steel wire; after the drop hammer 11 is stable and it is confirmed that there are no personnel or equipment below, release the connection between the lifting device and the drop hammer 11;

[0064] S6, turn on the test instrument, release the unhooking device 10, release the drop hammer 11, complete a test and record the test data;

[0065] S7, repeat steps S4-S6 to complete 3-5 groups of experiments;

[0066] S8. After the test is completed, dismantle the test device.

[0067] The present invention discloses a drop-hammer impact tensile test device and method for prestressed steel strands, aiming to solve the friction resistance problem of the drop-hammer test machine in the prior art, improve the accuracy of the test data, and extend the service life of the test machine. The invention discloses at least the following beneficial effects:

[0068] 1. Structural optimization: Through the innovative design of the connecting steel frame and the unhooking device 10, the stable suspension and precise release of the drop weight 11 are achieved, and the friction resistance caused by the guide rod is avoided, thereby improving the accuracy of the test.

[0069] 2. Easy operation: The design of the unhooking device 10 simplifies the release process of the drop hammer 11, making the test operation easier and faster.

[0070] 3. Improved durability: Due to the reduction of friction resistance, the drop weight 11 falls more smoothly, reducing the wear on the guide rod, thereby extending the service life of the testing machine.

[0071] 4. Test efficiency: Through the optimized test device design, the preparatory work before the test can be completed quickly, which improves the efficiency of the test.

[0072] 5. Enhanced safety: The design of the test device takes into account the safety of operation, and reduces potential risks during the test by ensuring that the drop weight 11 falls along a predetermined trajectory.

[0073] 6. Strong adaptability: The test device can adapt to drop hammers 11 of different weights, and the hammer weight can be adjusted by increasing or decreasing the number of hammer bodies assembled, thereby improving the flexibility of the test.

[0074] 7. Easy to disassemble and assemble: The design of the drop weight 11 and the guide member 15 allows for quick disassembly and assembly, facilitating the maintenance and care of the equipment after the test.

[0075] 8. Standardization of test methods: A standardized drop weight impact tensile test method is provided, including detailed test steps, to ensure the standardization of the test process and the comparability of the results.

[0076] The details not described in detail in the present invention are all conventional technical means well known to those skilled in the art.

[0077] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0078] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A drop weight impact tensile test device for prestressed steel strands, characterized in that: The invention comprises a connecting steel frame connected to a reaction frame crossbeam (5), and a drop hammer (11) suspended below the connecting steel frame through a decoupling device (10); a through hole is opened at the center of the drop hammer (11); a steel strand (12) passes through the drop hammer (11) through the through hole; an upper anchor end (8) of the steel strand (12) is fixed to the connecting steel frame, and an anchor end bearing plate (13) is installed on the lower anchor end (14); in a first state, the drop hammer (11) is kept stationary by the decoupling device (10); in a second state, the drop hammer (11) is released from the decoupling device (10), falls freely along the steel strand (12), and impacts the anchor end bearing plate (13).

2. The drop weight impact tensile test device for prestressed steel strand according to claim 1, characterized in that: The connecting steel frame comprises a first steel plate (1), a second steel plate (2), a third steel plate (3) and a fourth steel plate (4) which are arranged at intervals from bottom to top; the first steel plate (1), the second steel plate (2), the third steel plate (3) and the fourth steel plate (4) are horizontally fixed on four screw rods (7) by means of locking nuts (6); the third steel plate (3) and the fourth steel plate (4) are respectively pressed against the bottom surface and the top surface of the reaction frame cross beam (5); the upper anchoring end (8) of the steel strand (12) is connected to the center of the second steel plate (2); the decoupling device (10) is connected to the first steel plate (1); and a U-shaped notch (100) for accommodating the steel strand (12) to pass through is opened in the center of the first steel plate (1).

3. The drop weight impact tensile test device for prestressed steel strand according to claim 2, characterized in that: Two dehooking devices (10) are provided, and the two dehooking devices (10) are symmetrically arranged on both sides of the U-shaped notch (100).

4. The drop weight impact tensile test device for prestressed steel strand according to claim 3, characterized in that: The decoupling device (10) comprises a device body (101), a decoupling mechanism movable in the device body (101), and a passive hanging part (108) clamped in the decoupling mechanism, wherein the drop weight (11) is fixedly connected to the bottom of the passive hanging part (108) by connecting a steel wire rope (109); the inner cavity of the device body (101) comprises a reduced diameter section near the top, and the reduced diameter section comprises two facing reduced diameter inclined surfaces (102); the decoupling mechanism comprises a central block (103) sliding in the inner cavity of the device body (101), and movable blocks (104) are symmetrically hinged on both sides of the central block (103), and the two said movable blocks (104) are symmetrically hinged on both sides of the central block (103). A spring (105) is connected between the movable blocks (104). In an initial state, the spring (105) pulls the bottom ends of the two movable blocks (104) closer together, clamping the passive hanging component (108) between the two movable blocks (104). An unlocking wire rope (107) is connected above the central block (103). When the unlocking wire rope (107) is pulled, the two movable blocks (104) move upward to the reduced diameter section. The reduced diameter inclined surface (102) guides the top ends of the two movable blocks (104) closer together, so that the bottom ends of the two movable blocks (104) move away from each other, and the passive hanging component (108) is removed from between the two movable blocks (104).

5. The drop weight impact tensile test device for prestressed steel strand according to claim 2, characterized in that: The second steel plate (2) is supported by an insert (9) above, and a weight groove (92) is provided on one side of the insert (9) and radially penetrates to the center thereof, and the center inner diameter of the weight groove (92) is smaller than the outer diameter of the upper anchor end (8) of the steel strand (12), and a reserved hole (21) is provided in the center of the second steel plate (2) and passes through the upper and lower parts, and the upper anchor end (8) of the steel strand (12) passes through the reserved hole (21) and is supported above the insert (9).

6. The drop weight impact tensile test device for prestressed steel strand according to claim 5, characterized in that: A positioning pin (91) is protruded from the bottom of the plug-in unit (9), and a positioning groove (22) matching with the positioning pin (91) is formed on the second steel plate (2).

7. The drop weight impact tensile test device for prestressed steel strand according to claim 1, characterized in that: It also includes a gravity accelerometer installed on the drop weight (11).

8. The drop weight impact tensile test device for prestressed steel strand according to claim 1, characterized in that: The two ends of the through hole are detachably mounted with guide pieces (15), the center of the guide piece (15) is provided with a guide hole (151), and the steel strand (12) passes through the guide piece (15) and the drop weight (11) through the guide hole (151).

9. The drop weight impact tensile test device for prestressed steel strand according to claim 1, characterized in that: The drop hammer (11) comprises a plurality of hammer bodies, which are connected in sequence in a vertical direction, and the through holes of the hammer bodies are interconnected. The weight of the drop hammer (11) can be adjusted by increasing or decreasing the number of the hammer bodies.

10. A drop weight impact tensile test method, using the drop weight impact tensile test device for prestressed steel strands according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Assemble and connect the steel frame; S2, installing the assembled connecting steel frame onto the reaction frame crossbeam (5); S3, laying buffer sand on the ground below the connecting steel frame; S4, passing the upper anchoring end (8) of the steel strand (12) through the drop weight (11) and fixing it on the connecting steel frame; S5, sending the drop weight (11) to a preset height position through a lifting device, and fixing it to the unhooking device (10) by connecting the steel wire rope (109), and releasing the lifting device after the drop weight (11) is stable, thus completing the preparation work before the test; S6, open the test instrument, release the unhooking device (10), release the drop weight (11), complete a test and record the test data; S7, repeat steps S4-S6 to complete 3-5 groups of experiments; S8. After the test is completed, dismantle the test device.

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